(a) Field of the Invention
The present invention relates generally to a communication signal receiver/transmitter system and, more particularly, to a slot array antenna receiver system having a planar waveguide-to-microstrip adapter and a method of installing the same in a building.
(b) Description of Related Art
Satellite and ground based communication systems relay or send electronic communication signals, including audio, video, data, audio-visual, etc. signals, to or from any portion of a large geographical area, such as the continental United States. A satellite-based signal distribution system generally includes an earth station that modulates a carrier frequency with an audio/visual/data signal and then transmits (uplinks) the modulated signal to one or more, for example, geosynchronous satellites. The satellite(s) amplify the received signal, shift the signal to a different carrier frequency band and transmit (downlink) the frequency shifted signal to earth for reception at individual receiving units. Other known communication systems, such as cellular systems, use a number of transmitters spaced throughout a geographical region to relay communication signals to individual receiver units within the region. In some of these systems, the individual receiving units may transmit a signal via a satellite or other transmitter to a base station, an earth station, or to other receiving units. Still other communication systems send signals to receiver units within a smaller geographical area such as a city, a block, or a building, or send signals directly between two points.
Certain of these satellite and/or ground based communication systems, including some commercial and military mobile communication systems as well as a direct-to-home satellite system developed by DirecTV.RTM. (known commercially as DSS.RTM.), use microwave/millimeter wave carrier frequencies, such as Ku band (ranging from approximately 12 GHz to 18 GHz) to transmit a signal from a satellite or other transmitter to one or more receiver units and/or vise-versa. Communication systems may operate in the millimeter wave (mmW) range above Ku-band and, in some instances, provide free-space point-to-point communication using the 60 GHz carrier frequency range where high free-space propagation signal losses occur. It has been suggested, for example, to locate a parabolic dish antenna on an exterior portion of a building to receive a communication signal at, for example, Ku-band, and then to retransmit the communication signal at V-Band (e.g., at or near the 60 GHz carrier frequency region) to receiving antennas associated with a number of receiving units within the building via transmitters that overhang the roof of the building. Of course, other microwave/millimeter wave carrier frequency bands can be used to transmit other types of communication signals between other ground-based transmitters (such as those disposed on towers, buildings, etc.) and receivers.
In these communication system configurations, it is desirable to use a Ku-band, a V-band (e.g., 60 GHz), or other receiving/transmitting antenna located on the exterior of a building to receive signals from or to transmit signals to a satellite transmitter/receiver, a roof-mounted transmitter/receiver, or other transmitter/receiver. Mounting an antenna on an exterior of a building may be difficult however, especially when the building is a multiple dwelling unit like a multiple story apartment building, condominium, etc. that has no balconies or other easily accessible structures on which the antenna can be mounted. In these instances, an installer must scale the outside of the building or lean out of a window of the building, drill a hole into or through a wall of the building and mount the antenna in or near the hole in the wall. This activity can be dangerous and time consuming and, in some cases, next to impossible without the aid of sophisticated ladders or other scaling equipment.
Furthermore, it is desirable that an exterior mounted antenna be compact so that it does not take up a lot of space at a receiver location, be low in profile so that it does not significantly deface the aesthetic appearance of the building on which it is mounted, and be relatively immune to environmental hazards such as rain, snow, etc. Still further, it is important that the antenna be inexpensive so that it may be used in widespread consumer-oriented communications applications, such as in satellite or other television signal communication systems.
It is known to use smaller dielectric loaded slot array antennas, such as those discussed in Robert S. Elliott, "An Improved Design Procedure for Small Arrays of Shunt Slots," IEEE Trans. Antennas Propagation, Vol. AP-31, No. 1, pp. 48-53 (Jan. 1983), or other dielectric loaded waveguide fed slot array antennas to receive microwave/millimeter wave signals. However, these antennas require the use of a waveguide-to-microstrip transition stage or adapter, such as one of those disclosed in Terry Edwards, "Foundations for Microstrip Circuit Design," 2nd Ed., pp. 233-239 (1992), which use a microstrip probe, a ridged waveguide transformer, or a fin-line to convert the received electric field from a waveguide to a microstrip transmission line where the receiver/transmitter modulator or demodulator is implemented. Unfortunately, these known waveguide-to-microstrip transition stages are generally complex, add significantly to the cost of an antenna/receiver system and are not easily coupled to a waveguide antenna in a compact manner or in a manner that enables the antenna to be conveniently mounted on the exterior of a building.